
The AP is 21,18,15,.............. . Which term of the given A.P. is zero?
Answer
536.4k+ views
2 likes
Hint: In order to solve this problem assume a term to be zero and then find the number of that term. Get the first term, common difference from the AP given.
Complete step-by-step answer:
The given AP is 21,18,15,..............
We can clearly see first term is = 21 = a ……(1)
And common difference can be calculated as - =d
So from the AP we can say = 18
Therefore, d = 18 – 21 = -3 ……(2)
So, d = -3
Let us assume the nth term to be 0.
Then, = 0 ……(3)
We know = a+(n-1)d
So we can do,
= 21+(n-1)(-3)=0 ……(From (1), (2) and (3))
21 + -3n+3=0
24=3n
n =
n = 8.
Hence, the 8th term of the AP is Zero.
Note: Whenever you face such types of problems obtain the first term and common difference from the given AP. Here in this question we have assumed the nth term to be zero then we have applied the formula of nth term of the AP. Proceeding like this you will get the right solution.
Complete step-by-step answer:
The given AP is 21,18,15,..............
We can clearly see first term is
And common difference can be calculated as
So from the AP we can say
Therefore, d = 18 – 21 = -3 ……(2)
So, d = -3
Let us assume the nth term to be 0.
Then,
We know
So we can do,
21 + -3n+3=0
24=3n
n =
n = 8.
Hence, the 8th term of the AP is Zero.
Note: Whenever you face such types of problems obtain the first term and common difference from the given AP. Here in this question we have assumed the nth term to be zero then we have applied the formula of nth term of the AP. Proceeding like this you will get the right solution.
Recently Updated Pages
Master Class 10 General Knowledge: Engaging Questions & Answers for Success

Master Class 10 Computer Science: Engaging Questions & Answers for Success

Master Class 10 Science: Engaging Questions & Answers for Success

Master Class 10 Social Science: Engaging Questions & Answers for Success

Master Class 10 Maths: Engaging Questions & Answers for Success

Master Class 10 English: Engaging Questions & Answers for Success

Trending doubts
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths

Fill the blanks with proper collective nouns 1 A of class 10 english CBSE

Which one is a true fish A Jellyfish B Starfish C Dogfish class 10 biology CBSE

Why is there a time difference of about 5 hours between class 10 social science CBSE

What is the median of the first 10 natural numbers class 10 maths CBSE

Change the following sentences into negative and interrogative class 10 english CBSE
